Minecraft: here's one I made earlier

It's been dubbed virtual Lego, a place where people build fantasy worlds and drop in on past creations. As Minecraft turns five and tops 50m users, Tom Lamont assembles his dream construction team and steps into a land of opportunity, love and painful memories

Tom Lamont's interpretation of the Telecom Tower rises up from his fantasy island. Photograph: Mathieu Legault

"Let your surroundings load a bit," said Adam, a 27-year-old from New Jersey. "This thing's big." I stared at the fortress he was building as my laptop purred, loading details: the towers and battlements and a giant front door.

During the day, I knew, Adam was Adam Shefki, a lawyer. He wore a suit to work. But right now, in avatar form, he was styled in tan leathers and a rocket pack, and he was figuring out how to make that giant door open and shut on command. Adam was introducing me to Minecraft.

The most popular computer games tend to license the unfeasible. Hey: you're an international footballer. An assassin in 16th-century Rome. In Minecraft, which celebrated its fifth birthday last month, with worldwide sales hovering just under the 50m mark, the fantasy amounts to stiff labour. Construction work. Players are cast as architects – resource-rich architects with the power of flight, granted, but architects nonetheless. Play Minecraft and rather than compete for the World Cup or plot to kill a Borgia, it's preferred you act like a groundsman, or a Roman town planner, willing to put in hard hours with blueprints and shovel.

And somehow Minecraft has become a global sensation, prized by teenagers, adults and, in particular, seven- to 12-year-olds, whose parents tend to endorse the game precisely because it doesn't exalt unsavoury footballers or murder. It is used as a teaching aid in America and Scandinavia; it's a compulsory subject of study in at least one Swedish school. Recently, Denmark's ministry of environment commissioned a Minecraft-made replica of the country. All 85,000 square miles of it.

Adam's avatar. Photograph: Gerald Swanson for the Guardian

What is it like to play? Load Minecraft and you're tossed on to freshly generated terrain. Personal appearance can be tweaked (by default, the in-game avatar is male, T-shirted, black), but really you're here to build. Alone or in collaboration. Online or off. Against the clock and with limited resources, in Minecraft's hectic "survival mode", or with infinite cubes of materials and the serene freedom to arrange them – "creative mode".

You might start by exploring the area, hiking hills and wading through lagoons to find a promising plot of land. Ground is cleared with one button, building blocks placed with another. The game's physics start to make sense as soon as you've hacked down a few trees, made a tunnel and put up a crude monument to yourself. Blocks can be gummed together in unlikely ways, side on, in zigzags, forming queasy, top-heavy clusters, but they can't be made to float (not without clever fiddling). To make a hut, it's best to start from the ground up. There are materials such as carpet squares and windowpanes for prettifying the work.

Minecraft is versatile, too. You won't be satisfied with that hut for long, however attractive the carpet, and will want to graduate to bridges and castles. Whole blocks of Manhattan have been recreated in the game. A 1:1 replica of the Titanic. London's Olympic Park. Jurassic Park. Building is of such importance here that the verb has been made a noun: structures are referred to by Minecraft fans as "builds". When groups band together online, better to attempt something epic, they refer to themselves as "build teams". Adam introduced me to his build team, among them a British woman called Maria Bovor. A 29-year-old illustrator from Worcester, Maria appeared in the game as a cyborg. I was wearing a tuxedo with golden spats and we complimented each other on our outfits, speaking by writing messages that appeared on screen in bright, blocky text.

Maria told me that when she first saw Minecraft in action, the graphics angular and awkward, she dismissed it: "Bad looking." The power of the game, though, was in the ambitions it tickled, and she got hooked once she'd knocked up a decent replica of her own house, then later a desert city with a network of underground commuter canals.

When she met Adam, he was working on a statue of the Greek god Atlas that would require the meticulous placing of 300,000 gravel-grey blocks. She was building a castle made of ice. "It was cute," Adam said, "to see how excited she was about all the secret entrances." They agreed to collaborate.

Double-tapping a special button in Minecraft enables flight; together Adam, Maria and I flew to visit the Atlas statue. Completed in 2012, it loomed over us, 150m tall, about the height of the British Telecom Tower. When I admired it Adam said, "There were other statues, tests."

"We don't talk about the tests," Maria said.

How long had they been at work together? Adam: "Oh lord. Depressing thought to tally." Maria: "Take what he says, then double it at least." Adam: "Months of free time, probably."

Having manipulated millions of pixelated blocks in each other's company, Adam and Maria became a couple last year. She recently visited him in New Jersey for an extended stay. "Sometimes," Adam told me, "a game spills out into real life."

This game! Downloaded on to 21m phones, bought for more than 13m consoles, installed on 15m PCs and Macs, it is is the third bestseller of all time, after Tetris and that sporty one for the Nintendo Wii. The Official Construction Handbook, an introductory guide to the game, debuted at the top of the book charts last Christmas. In April, Minecraft received the priceless flattery of a parody on The Simpsons. Warner Bros had already announced they were making a movie.

Meanwhile, at the user end, ambitious projects continued to roll out. A Scottish sixth-former made a stunning replica of the Winter Palace in St Petersburg. Chinese history enthusiasts laboured to reconstruct Beijing exactly as it had appeared in 1751. I visited, exploring this Qing-dynasty city via monorail, and learned that construction was due for completion in "July 2023". Was it wise, I wondered, while riding a pretty route from the Gate of Divine Might to the Palace of Heavenly Purity, to plan to invest so much time?

Adam had surrendered months to Minecraft. "Picture my parents," he said. "In their 60s, lovely people… They don't understand at all what I do with my leisure time. It's a hard thing to show people. 'Hey! Come over and look at this giant virtual thing I built!' For some people, that abstraction never makes sense. It's just numbers."

Maria was more at ease. People commit to all kinds of activities, she said, "for the process, for the memories... The argument that there is nothing tangible at the end of it doesn't hold sway. There's nothing to stop me opening old builds and going back to them. Rediscovering your old builds" – and she had once made a crumbling Moroccan city, a town square, a giant floating sphere – "is a massive nostalgia trip. Like opening an old photo album."

This is a feeling shared by Markus Persson, the game's creator. He tells me, simply, "The journey is the goal." A thoughtful, bearded 34-year-old, Persson is widely known by his internet nickname, Notch. For a while now, he has earned several hundred thousand pounds a day and is about to move into the most expensive flat, per square metre, in Stockholm. Still, those names – Persson, Notch – feel apt for a man who has been hauled from anonymity by Minecraft's success and who often gives the impression he would like to go back to it. "I'm not sure how I feel," Persson wrote on Twitter after the Simpsons homage was broadcast. "I still feel a bit like it's just this small game I made at home."

Mojang is run by Persson and his colleagues in a relaxed, let's-work-in-our-underpants fashion – authentic breeziness that so many tech firms strive to fake. Every Friday, its 35 staff down tools to play console games. Buyout efforts are not welcome ("They can play it like everyone else," Persson said in 2011, after industry kingpin EA began to circle), and not long ago a collaboration with Facebook was refused on the quite brilliant grounds of Facebook's creepiness. ("Their motives are too unclear," Persson wrote in a blogpost.) While we chatted over email, he posted a tweet that suggested he really was working in his underpants that afternoon.

"Happiness is a moment, not a state," he said, when I asked if his creation had made him happy. "Minecraft has definitely been the cause of many of those moments."

It was the encouragement I needed to play for myself. Impressed by Adam and Maria's camaraderie, I decided to assemble a small build team of my own. The sixth-former who'd made the Winter Palace, Matthew Fulton-Peebles, agreed to join, as did Pablo Zazueta, a friend's nine-year-old son, who was given special permission to play after school. Adam and Maria said they'd chip in with some of the heavy clicking. Would it be enough?

I browsed forums, looking for builders. "Minecraft is my life," a young Californian called Nathan had posted, although by the time I got in touch, his interest had flagged. Others appeared to expect payment for building work, their quotes varying wildly. A Serbian undergraduate called Branko advertised that, "for only $5, I will work for you for two hours in Minecraft". An Australian teen, Jayden, was banned from a forum for asking for up to £150 per job. I liked the sound of both. (Neither gave me their surnames.)

Olivia's avatar. Photograph: Gerald Swanson for the Guardian

My team grew. Olivia Quezada, a student from Texas, had advertised her expertise online. "My goal is to create worlds that are beautiful… Could it happen? Did it happen? You decide." I employed her for a small fee. Joseph White, a 21-year-old web designer whom I'd met on a forum for Minecraft enthusiasts, said he'd assist for free. I found a trio of Italian landscaping specialists who designed me a basic island, with palm trees, a lagoon and expanses of flat terrain – a blank canvas on which to build. We were ready to start. I needed only to tell the team what to do.

Past, hardy Minecrafters, I knew, had made the Eiffel Tower and a Thames-spanning Tower Bridge. There had been at least a dozen efforts to erect a Tower of Babel. As far as I was aware, no one had attempted the BT Tower, and I thought my team might take a shot at it.

Sketches were made. We'd build the Telecom Tower… No, two Telecom Towers, surrounded by a rollercoaster. With a moat. And a tennis court. When Branko logged on, I cautiously explained my plan. He was unfazed: "Where do you want the rollercoaster?" he asked, already hacking down trees.

Digital Lego, virtual Lego, a Lego that doesn't hurt when you step on it: these are the terms used to describe Minecraft to the unfamiliar. Peter Molyneux, creator of the 1990s computer game Dungeon Keeper, to which Minecraft owes a distant debt, has called it "social Lego". Will Wright, creator of SimCity, another significant forebear, once pointed out that Minecraft is like Lego in that it combines "accessibility and depth… complex output with simple input". Persson grew up a fan of the plastic bricks. "I used to build exactly what was on the box," he told me.

Persson was raised in Edsbyn, in the Swedish countryside, then later in Stockholm. His father taught him to code when he was young, and an interest in game design took root. After college and a stint as a web designer, in his late 20s he joined Stockholm games company King. For his employers (nine-to-five) and for himself (around the edges), he spent hundreds of hours making games, many with flatly explanatory titles: Carnival Shootout; Blast Passage; Bunny Press, in which bunnies were crushed in a press.

His work on a new, vaguer project called Cave Game began in spring 2009. After a few days, he had a promising prototype and a better title: a compound of words that highlighted the game's major activities, mining holes and crafting buildings. By the end of the first week, Persson told me, "pretty much the final version of Minecraft was there". He put it online, asking £5 a copy. Over a year, as development progressed, around 20,000 gamers paid.

He left King to found Mojang in summer 2010. By early 2011, when the sign on the office door was still written in green felt-tip, sales of Minecraft were past a million. A finished £12 version of the game was ready for sale in November 2011. Persson celebrated by opening a new box of Lego. He was already quite rich.

I was a Lego devotee as a boy, and perhaps those of us who grew up with that toy will wonder about the soundness of Persson's digital imitation. How could Minecraft, played on a screen, compare? On my island, as two Telecom Towers rose steadily towards the sky, I came to appreciate that the major advantage Minecraft has over Lego is scale.

Tom's avatar. Photograph: Gerald Swanson for the Guardian

The essential Lego block is the size of a thumb. Squeeze together enough of them and you might get something the size of a shoebox. Minecraft blocks are bigger – much: though viewed and manipulated within the limits of a computer screen, they're about waist high in relation to your in-game avatar. Pile up 10 and it's a structure that looms impressively. Pile up 100...

It took teenagers Jayden and Olivia a matter of hours to assemble my Telecom Towers, foundations, windows, ranks of satellites, everything. Meanwhile, Branko knocked together the rollercoaster, every square of wood and segment of rail placed by hand. When he was finished, I was allowed to ride it.

For the most part, I floated about the treetops while construction went on, overseeing as avatars flew about, sloughing off blocks, pausing to consider a tricky curve or corner, and sloughing again. I assisted with the work where I could, but probably I was most use to nine-year-old Pablo, with whom I built a handsome doghouse. At one point, we put out fires together, when a volcano he'd made started burning down my island's trees.

I asked questions of the team as they built. Otherwise, for long periods, everyone lapsed into silence. Time passed quickly, a fact that Minecraft makes players very aware of, with a square-shaped sun programmed to rise and set every 20 minutes. I began to find the repetitiveness of it all quite soothing. My team said this was a famous part of Minecraft's appeal. "I suppose I go into a creative trance when I build," Matthew said. Olivia had a psychology exam coming up, her end-of-school prom to prepare for, and she welcomed the chance to "forget external stress". Adam said, "I made my way through law school playing Minecraft. When I was studying for finals, I'd play the game and put audio recordings of my lectures on in the background. It kept me sane."

Building seemed to open people up. When we were alone, Branko admitted an aspiration to one day run his own hotel. He also mentioned a girlfriend he'd met through the game, and the house they'd built together on a public Minecraft server. "With a balcony and a pool."

When people talk in Minecraft, they have to stop building to type. Their little avatar goes still; its square head appears to dip. When someone is about to tell you something in the game, they look mournful. Branko told me about the time he logged on to find that the house he'd built with his girlfriend had been deleted by accident. "Of course, we'd broken up in the meantime... Minecraft has made me sad many times."

Joseph, the 21-year-old web designer, logged on to my island and found a spot on top of a remote hill where he began to erect a tower. It had a beam of light that projected from the roof and appeared, from where I was floating, to be a monument to something. Joseph told me he'd started playing Minecraft in its early days, when he was a teenager. The pared-down graphics made it one of the few games he could run on a slow computer.

"Life was… tough?" said Joseph, who grew up in Canada. "We were living in a cabin in the middle of nowhere." In 2011, his mother remarried and Joseph, who said he suffered from Asperger syndrome, found it hard to connect with his new stepfather. Eventually they discovered a shared interest in computing, and started playing Minecraft together, becoming close that way.

His stepfather died in 2012. "No warning," said Joseph, who on the night it happened was woken up by the ambulance. Afterwards, he logged on to his stepfather's computer and found a half-finished Minecraft world. Built in secret, it might have been meant as a surprise. Loading it "felt surreal", Joseph told me. "One of the final feelings of, 'He's actually gone.'" He saved the world on to multiple hard drives, worried about losing it. "I'm glad to have this part of him."

A teenager playing Minecraft. Photograph: Voisin /Phanie/REX

When I told Persson about Joseph's story, he said, "Any personal memory of a lost one is valuable, regardless of form. Sometimes it's intangible, sometimes it's transient, and sometimes it's a physical artefact. I have no doubts being able to walk through a fictional world where someone left their imprint could be very powerful."

Persson lost his own father in 2011, a difficult time in his life during which he also separated from his wife. In a profile by Rolling Stone magazine, he said of his divorce that changes to his lifestyle (and you expect being profiled by Rolling Stone was just the sort of thing he meant) played a part. I got the impression that for Persson, as for Joseph and Branko, Minecraft was not a wholly positive force.

"Everything is strange and new and confusing," Persson said of his life since Minecraft got big. "I'm constantly surprised by it, but I've kind of given up reacting to it... So far, all my predictions about when Minecraft will go out of fashion have failed."

In the past, Persson has admitted feeling hampered by the expectant attention of millions. He has abandoned at least one follow-up game he was designing. When I chatted with him in May, prospects were better. Persson was "deep in code", day and night, he told me. He seemed to have rediscovered the high spirits of his Bunny Press days, too, and would go on to release - earlier this week - a new game called Cliffhorse. Programmed in a matter of hours, it cast players as roving, aimless horses – apparently the result of a private joke between Persson and his friends. (Sales have been middling.)

Meanwhile Minecraft, a game he stopped active work on years ago, continued to thrive: in May, total sales of the tie-in books approached a million. Lego, which had made an alliance with Persson in 2012, said it would expand its Minecraft-branded line. As for sales of the game itself, Persson thought it likely the 50 millionth copy had already gone, despite the lack of any formal announcement by Mojang. "We'll probably celebrate it the way we celebrate most milestones," he said. "By realising it happened some time ago and maybe having a glass of champagne."

It happened to be five years to the day since Persson had written his first line of Minecraft's code. Adam and Maria joined me on my island for one last building session.

We met beside the Telecom Towers, where Adam constructed an elaborate treehouse and Maria put up a watchtower. For my part, skulking under a canopy of trees, I tried to even out a tennis court that was badly misshapen. I hadn't even started on the moat. Beginning to feel the first prickles of boredom, I thought of young Nathan, for whom Minecraft was life, until it wasn't.

"I recognise that at some point things will stop happening," Adam said. Increasingly busy at work, he said, he'd felt his commitment to the game lessen. And then?

"Whatever I'm working on will fall into the ether of wherever builds go once people stop looking at them." When Maria last visited him, Adam said, they didn't play Minecraft at all: "She wanted to see America."

Our session came to an end. Adam had been staring at his screen for too long and logged off with a headache. Maria went, too, to watch the Eurovision song contest on TV. Alone, I took wing and did a last circuit of my island. Then I left: I had one more place to visit. Joseph had emailed me the save file of his stepfather's half-made world and suggested I take a look.

When I loaded it up, I found an expanse of flat terrain dominated by a lake. There was a castle on its banks and nearby an ornamental fountain, one that spouted not water but lava – the flourish, as I took it, of a middle-aged man who might have started playing this game to communicate with his stepson, but who wound up enjoying himself, finding his ideas irresistible. I discovered a secret tunnel that led away from the lakeside castle, out of the cellar and all the way under the water, to a secluded cove.

"Placing blocks is fun," Markus Persson had told me. "Even if we prevent ageing, even if we escape the solar system before the sun swallows the Earth, we will not survive. We're something that happens in the universe. We're a story."

Make the story good, was his point. Build a fortress. Build a tower. Build a secret tunnel that leads out under a lake.